The most common and most likely answer to this crossword clue is the 4 plus 3 plus 6 letter word OPEN AIR MARKET
I've seen this crossword clue in The Daily Telegraph
O
P
E
N
A
I
R
M
A
R
K
E
T
Buddy explains!
The straight part
We know that "Where all the goods will be sold out" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case where all the goods will be sold out = open air market.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.